There's a couple of misconceptions here:
Originally Posted by Ian Walker
Guys I know everybody prefers to blow the lines BUT an old
RVer taught me that the pink antifreeze is better BECAUSE
as you all know the TT's are all thrown together at the factory
& I'm sure anybody who has crawled underneath will agree with that.
The water lines are just hanging under the trailer and anything
just hanging will have a low point. When you blow the lines,
the air will pass over the low points and leave some water in the lines
so you introduce the possibility of frozen lines. Also there's a
possibility that some water line that you don't have access to
might freeze (Murphy's Law). So use air if you must but understand the possible consequences.
Water, in and of itself, freezing in a line will not hurt the line. What bursts the lines is water having no place to expand when it freezes. A few drops freezing in your lines will harm nothing. Good rule of thumb is that you can freeze water a distance of 10 pipe diameters if you have an air space at both ends, or 5 diameters if you have only an airspace at one end. A 2 inch slug of water in the low spot of a 1/2" line will not hurt a thing. Not that blowing the lines out will leave even that much. Done properly, the compressed air method will remove nearly ALL the water from the lines, leaving only the occasional droplet here and there.
Originally Posted by youroo
The OP states they do NOT want to use Pink AF,their Water pump will NOT be protected if they only use Air! Even though they state they have Never used the F/W tank or Pump,Water will still be Inside the Pump Chambers and it Will Freeze!
The pump in our campers are PD or positive displacement pump. That means for each revolution of the pump, you will get a fixed volume output of whatever goes in the inlet. These pumps are more than happy to pump air if you let them. If you drain the inlet side (by draining the FW tank) and run the pump, you will pump air, and thus expel all the water and have only air left in the pump.
I am going on 10 years of RV ownership with not ever putting pink stuff in my freshwater system. In fact, I have only bought 2 or 3 gallons of pink stuff in those 10 years just for the p traps and toilet bowl. I live in St. Louis and I assure you that it can
get as cold here as anywhere in the lower 48, and I sleep well knowing that my RV water system will be fine in spring, and I wont have to worry about the unpleasant residue of the pink antifreeze.
I'm not saying this to imply that there is a right way and a wrong way. If your comfort level is highest with pink antifreeze, then by all means, don't let me sway you. I just dislike when people imply (especially to newbies) that the blow-down way is ineffective and will hurt the plumbing. Either way works equally well.